Hello all,
I stumbled over "Iron Oxide Patinas" heat applied, which seems to me kind of a enameling process. Question: how exactly to do it and what kinds of oxides to use?
Who has experience with this process?

If you are not sure what I am talking about, here is a link to a shop which actually seems to do it: http://www.artfactory.com/door-grill-hand-forged-patina-finished-gvg12-p-5002.html

Have a nice day,
Andreas

The simplest form would be temper colors. A thin film of iron oxides form on the metal as it is heated from about 500F to about 700F forming straw, yellow, purple, then a few shades of blue then grey. This film by itself is delicate, but can be protected with lacquer or other clear finish.

Beyond this I am sure there is more thermo-chemistry involved, especially when they are showing blues, purples, yellows and whites and cite temperatures over 1000F. I do not know what their process would be.

Phil

Well they are quite proud of their product! I find their claim that "patinas last forever" to be very misleading if not downright fraudulent! While it is true that there will always be a patina (barring abrasion or chemical cleaning) to say that it "lasts forever" implies that it will be essentially unaltered... I know this to be UNTRUE! In fact I have found patina finishes generally quite fragile and dependent on high quality clear paint finishes for any durability that they do have. Unfortunately these clear finishes often damage the delicate qualities of the patinas that they are intended to preserve. To imply that their patina finishes are much more durable than paint finishes is a real stretch... to say that they "last forever" may be technically true but is clearly a very misleading claim! I wouldn't waste much time trying to figure out these guys "secrets" as I and many others are likely in possession already of more and better techniques. Really LOUD hornblowers like these are rarely really the leading experts that they portray themselves to be!

I do believe that they actually use some kind of vitrous enamel, which would be applied around this temperature and can have most colors using metal oxides. Definitely not talking here about temper colors.
What I am actually really looking for are alternatives to paint finishes, for various reasons. This one seems like something I would use.

But I totally agree on the hornblower issue, those guys do blow a lot and loud.

Enameling can be done a number of ways, and using reduction or oxidation pigments can make for serious colors. You will need a kiln of some type. Ceramics and ceramic glazes are the same basic technology. No, I don't know enough to tell you "read this, do that" but this is not new or novel technology.

Phil

Did ask them for more details and guess what, they answered. Their response: sorry this is proprietary information.
And only that. Oh well, did we expect anything more?

I will read into enameling, lets see what gives.

Thanks all

Any finish (on rustable steel/iron) that is brittle will fail much quicker than paint. Enamelling sounds brittle to me. Depends what you want to use it for, of course.
There is a world of different and interesting finishes for metals that can be found on the internet or in books, or will be told to you happily by members of this forum or other metal workers.
That website is impenetrably schizophrenic. A claim that they have a secret formula is very likely to be, like most secrets, either not really a secret, irrelevant, boring or wrong.

I was busting some enamel off tube just yesterday. It's not what I'd call "fragile." Stuff clings tenaciously. A good whack with a 3 pounder is what I needed to make it let go.

How did it stand up when you flexed the piece? Thick enamel bonded on a rigid substrate can be a lot tougher than a thin layer on something that flexes.

It was 1/4" thick wall 3" square tube. You want it flexed, you go flex it! :P

I was busting some enamel off tube just yesterday. It's not what I'd call "fragile." Stuff clings tenaciously. A good whack with a 3 pounder is what I needed to make it let go.

Thingmaker, you beat me to it! Yeah, enamel is no joke when it's done right. Plus the intent of a coating is atmospheric isolation/ protection for substances that oxidize.